In a multicarrier radio transmission system complex-valued symbols are assigned to at least a first subcarrier and a second adjacent subcarrier, wherein the symbols assigned to the second subcarrier are offset in frequency by half a subcarrier against the symbols assigned to the first subcarrier.
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1. A multicarrier radio transmitter for transmitting a plurality of complex-valued symbols, wherein at least a first subset of the plurality of symbols is assigned to a first subcarrier and a corresponding second subset of the plurality of symbols is assigned to a second, adjacent subcarrier, the transmitter comprising: one or more processors, one or more computer-readable non-transitory storage media having stored thereon computer-executable instructions that are executable by the one or more processors to instantiate in the storage media: at least one modulator containing a prototype transmit filter for pulse shaping the symbols assigned to the first and second subcarrier, wherein said modulator performs a frequency shift only to the symbols assigned to the second subcarrier by a bandwidth of half a subcarrier.
This invention describes a multicarrier radio transmitter designed to send complex-valued symbols. It assigns a first group of symbols to a primary subcarrier and a second group of symbols to an adjacent subcarrier. The transmitter operates using one or more processors that execute instructions stored on computer-readable media. These instructions instantiate a modulator. This modulator includes a prototype transmit filter responsible for pulse shaping both sets of symbols (those on the first and second subcarriers). Crucially, the modulator performs a frequency shift only on the symbols assigned to the second subcarrier, shifting them by half the bandwidth of a subcarrier. ERROR (embedding): Error: Failed to save embedding: Could not find the 'embedding' column of 'patent_claims' in the schema cache
2. The multicarrier radio transmitter of claim 1 , wherein the processors further instantiate in the storage media a prefix/suffix block for adding a cyclic prefix or a cyclic suffix to one block of modulated symbols, said block comprising a plurality of symbols assigned to the first subcarrier and a plurality of symbols assigned to the second, adjacent subcarrier.
The radio transmitter described above also adds a cyclic prefix or cyclic suffix to blocks of modulated symbols before transmission. Each block contains a set of symbols from the first subcarrier and a corresponding set of symbols from the second, adjacent subcarrier. This prefix/suffix is added to improve signal quality and mitigate inter-symbol interference during transmission.
4. The multicarrier radio transmitter of claim 1 , wherein the prototype pulse shaping filter is a root raised cosine filter.
In the radio transmitter described previously, the transmit filter that shapes the pulses of the signals on the first and second subcarriers is a root raised cosine filter. This specific type of filter helps to minimize interference between adjacent subcarriers and improve the overall signal quality of the transmitted signal.
5. A multicarrier radio receiver for receiving a multicarrier signal representing complex-valued symbols assigned to at least a first and a second, adjacent subcarrier, wherein symbols assigned to the second subcarrier are shifted in frequency by half a carrier bandwidth against symbols assigned to the first subcarrier, the receiver comprising: one or more processors, one or more computer-readable non-transitory storage media having stored thereon computer-executable instructions that are executable by the one or more processors to instantiate in the storage media: a first demodulator applying a Hermitian of a modulator matrix applied to symbols of the first subcarrier; a second demodulator applying a Hermitian of the modulator matrix applied to the symbols of the second, adjacent subcarrier; and a selector receiving the demodulated symbols from the first and the second demodulator respectively and outputting only the real part of symbol or only the imaginary part of a symbol.
A radio receiver receives a multicarrier signal containing complex-valued symbols on at least two adjacent subcarriers. The symbols on the second subcarrier are frequency-shifted by half a subcarrier width relative to the first subcarrier. The receiver includes a first demodulator that uses a Hermitian transform of a modulator matrix to demodulate symbols from the first subcarrier. A second demodulator uses a similar Hermitian transform to demodulate symbols from the second subcarrier. A selector then chooses either the real or imaginary part of each demodulated symbol from both demodulators as the final output, effectively recovering the transmitted data.
6. The multicarrier radio receiver of claim 5 , wherein the processors further instantiate in the storage media a prefix/suffix remover for removing a cyclic prefix or a cyclic suffix from a block of modulated symbols, said block comprising a plurality of symbols assigned to the first subcarrier and a plurality of symbols assigned to the second, adjacent subcarrier.
The radio receiver described above also includes a prefix/suffix remover. This component removes the cyclic prefix or suffix from each block of received symbols, which contain symbols from both the first and second subcarriers, before demodulation. Removing the prefix/suffix prepares the symbols for accurate demodulation and data recovery.
7. A multicarrier radio transmission method, implemented at computing system that includes one or more processors and one or more computer-readable non-transitory storage media having stored thereon computer-executable instructions that are executable by the one or more processors to instantiate in the storage media at least a prototype transmit filter, the method for transmitting a plurality of complex-valued Quadrature Amplitude Modulation (QAM) symbols, where at least a first subset of the plurality of symbols is assigned to a first subcarrier and a corresponding second subset of the plurality of symbols is assigned to a second, adjacent subcarrier, the method comprising: modulating the symbols assigned to the first and second subcarrier by the prototype transmit filter for pulse-shaping; and shifting in frequency by a bandwidth of half a subcarrier only the symbols assigned to the second subcarrier.
A method for transmitting data using multiple subcarriers involves processing complex-valued Quadrature Amplitude Modulation (QAM) symbols. The symbols are divided into two subsets. The first subset is assigned to a first subcarrier. The second subset is assigned to a second subcarrier that is adjacent to the first. The symbols on both subcarriers are then modulated using a prototype transmit filter (pulse shaping). The symbols assigned to only the *second* subcarrier are then shifted in frequency by a bandwidth equal to half the width of a subcarrier.
8. The multicarrier radio transmission method of claim 7 , comprising the step of adding a cyclic prefix or a cyclic suffix to one block of symbols, said block comprising a plurality of symbols assigned to the first subcarrier and a plurality of symbols assigned to the second, adjacent subcarrier.
The multicarrier radio transmission method described above also involves adding a cyclic prefix or cyclic suffix to a block of symbols before transmission. The block includes symbols from both the first and second subcarriers. Adding the prefix or suffix helps improve the signal quality and reduce interference during transmission.
10. A multicarrier radio receive method, implemented at computing system that includes one or more processors and one or more computer readable non-transitory storage media having stored thereon computer-executable instructions that are executable by the one or more processors to instantiate in the storage media at least a first demodulator, a second demodulator, and a selector, the method for receiving a multicarrier signal representing complex-valued symbols assigned to at least a first and a second, adjacent subcarrier, wherein symbols assigned to the second subcarrier are shifted in frequency by half a carrier bandwidth against symbols assigned to the first subcarrier, the method comprising: the first demodulator applying a Hermitian of a modulator matrix applied to symbols of the first subcarrier; the second demodulator applying a Hermitian of the modulator matrix applied to the symbols of the second, adjacent subcarrier; and the selector receiving the demodulated symbols from the first and the second demodulator respectively and outputting only a real part of symbol or only an imaginary part of a symbol.
A method for receiving a multicarrier signal involves processing complex-valued symbols transmitted on at least two adjacent subcarriers. The symbols on the second subcarrier are frequency-shifted by half a subcarrier width relative to the first subcarrier. The method applies a Hermitian transform of a modulator matrix to the symbols of the first subcarrier using a first demodulator. A second demodulator similarly applies a Hermitian transform of the modulator matrix to the symbols of the second subcarrier. Finally, a selector chooses either the real or imaginary part of each demodulated symbol as the final output.
11. The multicarrier radio receive method of claim 10 , comprising a removing a cyclic prefix or a cyclic suffix from a block of modulated symbols, said block comprising a plurality of symbols assigned to the first subcarrier and a plurality of symbols assigned to the second, adjacent subcarrier.
The multicarrier radio receive method from above also includes removing a cyclic prefix or cyclic suffix from each block of received symbols, where each block contains symbols transmitted on the first subcarrier and the second adjacent subcarrier.
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December 7, 2015
April 18, 2017
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